A steering column assembly is an apparatus which is connected to a steering wheel to steer in response to a manipulation of a driver. A steering column assembly is generally configured to allow a tilt motion and a telescopic motion for a convenience of a driver. A tilt motion regulates an angular position of a steering wheel, and the telescopic motion regulates a longitudinal position of a steering column. Also, a locking device is provided which selectively allows the tilt motion and the telescopic motion. The tilt motion and the telescopic motion are restricted so as to maintain a position of the steering wheel when the locking device is in a locking state, and the tilt motion and the telescopic motion are allowed when the locking device is in an unlocking state.
A steering column assembly may be configured to be able to be collapsed while absorbing impact energy at the time of impact such a moment of vehicle collision. That is, when a driver crashes into a steering wheel, an inner jacket of a steering column moves into an outer jacket by impact force so that a steering column is collapsed, and during this process impact energy is absorbed. A steering column having this function is generally called a collapsible steering column.
In order to realize such an energy absorption function, various methods such as a method of interposing a tolerance ring between an inner jacket and an outer jacket, a method of using an energy absorption strap, a method of using deformation of locking teeth or the like have been introduced.
Such a collapsible steering column has corresponding two locking teeth for fixing an outer jacket and rotation of one of the two locking teeth occurs in a conversion between a locking state and an unlocking state, and in such a rotation there is a problem in that collision between the two locking teeth may cause noise and abnormal feeling. Also, since impact is applied in a state that two locking teeth are engaged with one another, there is a problem in that impart energy cannot be effectively absorbed at an early stage of collapse.